WO1980002205A1

WO1980002205A1 - Device for measuring a certain amount of liquid

Info

Publication number: WO1980002205A1
Application number: PCT/SE1979/000074
Authority: WO
Inventors: N Wihlborg
Original assignee: Tecator Instr Ab; N Wihlborg
Priority date: 1979-03-30
Filing date: 1979-03-30
Publication date: 1980-10-16
Also published as: EP0025782A1

Abstract

A device for such measurement of a certain amount of liquid (14a) that the ratio of the weight of the liquid to the weight of a sample (15) is L2:L1, has a container (1) for holding a liquid (14). At a certain level, the container (1) has an overflow which communicates with a collecting vessel (4). A lever (8) is disposed above the container (1) and carries a scale pan (10) for holding the sample and suspended on the lever (8) at a distance L2 from the fulcrum (9) thereof. A float (12) is connected to the lever (8) at a point spaced a distance L1 from its fulcrum (9) and extends down into the container (1) to be carried by liquid (14) therein.

Description

DEVICE FOR MEASURING A CERTAIN AMOUNT OF LIQUID

The present invention relates to a device for such measurement of a certain amount of liquid that the ratio of the weight of the liquid to the weight of a sample is in a fixed relative ratio of L₂:L₁. In sample analysis, a reactant is sometimes added which is in the form of liquid whose weight is proportional to the weight of the sample. Generally, the sample is first weighed and the liquid is then added to the sample in a volume which corresponds to a weight determined by the weight of the sample. When this volume is determined, regard must be paid to the temperature of the liquid. Thus, this method entails relatively complicated and time-consuming weight and volume determinations.

The object of the present invention is to provide a device which permits measuring a certain amount of liquid in a very simple manner. According to the invention, this object is achieved by the provision of a device, characterized by a container which is adapted to hold liquid and has an overflow at a certain level; a collecting vessel which communicates with the overflow; a lever which is disposed above the container; a scale pan for holding the sample and suspended on the lever at a distance L₂ from the fulcrum thereof; and a float which is connected to the lever at a point located at a distance L₁ from the fulcrum thereof, and which extends down into the container to be carried by liquid therein.

The invention will be more fully described hereinbelow with reference to the accompanying drawings, in which:- Fig. 1 is a partial section illustrating a device according to the invention in an initial position of use, and

Fig. 2 is a partial section illustrating the device in an end position. A cylindrical container 1 is divided by a partition 2 into an upper chamber 3 ahd a lower chamber 4. The chambers 3 and 4 communicate with each other by means of a pipe 5 which extends sealingly through the partition 2 and passes- a distance up through the upper chamber 3. At its base, the lower chamber 4 has an outlet 6 with a cock 7.

A lever 8 which is pivotal about a fixed fulcrum 9, is disposed above the container 1 and carries a scale pan 10 in the vicinity of its one end. The pan 10 is pivotally suspended on the lever 8 at a distance L₂ from the fulcrum 9 of the lever. Two equally long arms 11 are pivotally connected at one end to the lever 8 at a point located at a distance L₁ from the fulcrum 9 of the lever. At their opposite ends, the arms 11 are connected to a cylindrical float 12 which extends down into the upper chamber 3 of the container 1. The float 12 has a through centre bore 13 whose diameter is greater than the outer diameter of the pipe 5 and which receives the pipe 5. When the device is to be used for such measurement of a certain amount of liquid that the ratio of the weight of the liquid to the weight of a sample is L₂:L₁, the cock 7 is opened and the upper chamber 3 is thereafterfilled with liquid 14 up to the upper end of the pipe 5, whereupon the cock 7 is closed. The liquid 14 contained in the upper chamber 3 thus carries the float 12, the arms 11, the lever 8 and the scale pan 10. Now, the device is in the starting position of use shown in Fig. 1.

A sample 15 of possibly unknown weight m is placed in the scale pan 10, and the lever 8 and thus the float 12 are pressed downwardly such that liquid in the upper chamber 3 of the container 1 is displaced so as to descend by the pipe 5 into the lower chamber 4. When equilibrium has been regained, the following equation applies: M · L₁ = m · L₂, where M is the weight of' the liquid 14a displaced to the lower chamber 4. The ratio of the weight M of the liquid 14a displaced to the lower chamber 4 to the weight of the sample 15 thus is L₂:L₁.

The ratio L₂:L₁ may of course be varied, if desired. Thus, for example, the lever may have a plurality of suspension points at suitable distances from the fulcrum 9 to permit changing the factor L₂ and thus the ratio L₂:L₁.

As mentioned above, the diameter of the bore 13 is greater than the outer diameter of the pipe 5. As regards the dimensions of the bore 13, it should be noted that its diameter should be so great that the float 12, within certain limits, is laterally movable. Such a lateral movement is required, since the connection point P between the arms 11 and the lever 8, when the pan 10 is loaded, will move along a part of a circle C with the radius L₁. From the initial position shown in Fig. 1, the point P will thus move first to the right and, if the load in the pan 10 is sufficiently great, then to the left. Since in this example the arms 11 are of equal length, the point P will necessarily be located on the centre line of the float 12, which means that the centre line and thus the float 12, like the point P, are moved laterally when the scale pan 10 is loaded.

Claims

1. Device for such measurement of a certain amount of liquid (14a) that the ratio of the weight of the liquid to the weight of a sample (15) is L₂:L₁, characterized by a container (1) which is adapted to hold a liquid (14) and has an overflow at a fixed level; a collecting vessel (4) which communicates with the overflow; a lever (8) which is disposed above the container (1); a scale pan (10) for holding the sample and suspended on the lever (8) at a distance L₂ from the fulcrum (9) thereof; and a float (12) which is connected to the lever (8) at a point located at a distance L₁ from the fulcrum (9) thereof, and which extends down into the con tainer (1) to be carried by liquid (14) therein.

2. Device as claimed in claim 1, characterized in that the container (1) is divided by a partition (2) into an upper chamber (3) for holding liquid and a lower chamber (4) forming the collecting vessel, and that the chambers (3, 4) communicate with each other by means of a pipe (5) which extends through the partition (2) and up into the upper chamber (3) and whose upper end forms the overflow.